Search

Thanks to recent improvements in biological engineering, the idea of building a synthetic minimal cell that is able to replicate itself using a minimal amount of components has recently emerged as an ambitious goal that may be feasible to achieve in the long term. Following a bottom-up approach, two essential elements are required to provide the fundamental functionality of cellular division: a lipid membrane for confinement and a protein machinery to carry out fission. We have developed a technique to produce cell-size liposomes by means of a microfluidic device, which provides an innovative way to obtain monodisperse membrane confinements with a fine control over the concentrations of the solutions inside and outside the membrane (see the contribution by S. Deshpande in this conference). To these liposomes, we administer a minimal form of the divisome machinery of E. coli, viz., the proteins that constitute the Z-ring, a highly dynamic structure responsible for the membrane's constriction and fission. A central element of the Z-ring is FtsZ, a protein that, under GTP hydrolysis, polymerizes into filament structures that have been suggested to provide the force to constrict the membrane. Using our microfluidics and fluorescence microscopy, we temporally resolve the FtsZ filaments formation and their interaction with the membrane anchor proteins FtsA and ZipA, studying the entity of the liposome deformation to optimize the crowding conditions required for the divisome machinery to better perform its constrictive action on the membrane.

Passage of polymers through pores narrower than the hydrodynamic diameter is impeded by an entropic penalty for their confinement. This might be balanced by an attractive interaction with the pore ...

Structural analysis, supported by biochemical, mutagenesis and computational evidence, indicates that the peptidyltransferase centre of the contemporary ribosome is a universal symmetrical pocket composed solely of rRNA. This pocket seems to be a relic of the proto-ribosome, an ancient ribozyme, which was a dimeric RNA assembly formed from self-folded RNA chains of identical, similar or different sequences. This could have occurred spontaneously by gene duplication or gene fusion. This pocket-like entity was capable of autonomously catalysing various reactions, including peptide bond formation and non-coded or semi-coded amino acid polymerization. Efforts toward the structural definition of the early entity capable of genetic decoding involve the crystallization of the small ribosomal subunit of a bacterial organism harbouring a single functional rRNA operon.

We studied local budding and tubulation induced in highly oblate lipid vesicles by the anchoring of either polymers having a hydrophilic backbone and grafted hydrophobic anchor groups, or by oleoyl-coenzyme A, an amphiphilic molecule important in lipid metabolism. The dynamics of bud formation, shrinkage, and readsorption is consistent with an induced spontaneous curvature coupled with local amphiphile diffusion on the membrane. We report a novel metastable state prior to bud readsorption.